The present invention relates to a multi-array disk apparatus and, more particularly, to a multi-array disk apparatus having a double array controller arrangement.
Conventionally, in an array disk apparatus having one array controller, and a logical drive constituted by a double logical structure disk arrangement, even if one logical structure disk breaks down due to a fault, the other logical structure disk is operable. The faulty disk is replaced with a new one and then recovered, so the system is not influenced. If, however, a fault occurs in the array controller, the logical drive cannot be used.
In the prior art, therefore, array controllers 52 and 53 constitute a double array controller arrangement, as shown in FIG. 7. Even if a fault occurs in the array controller 52, the array controller 53 can control a logical drive 71 constituted by logical structure disks 57 and 58. In FIG. 7, the array controllers 52 and 53 respectively comprises host interfaces 61 and 65 for host devices 69 and 70, array control circuits 62 and 66, and I.sub.-- SPCs (Initiator SCSI Protocol Controllers) 63, 64, 67, and 68. This technique is disclosed in Japanese Patent Laid-Open Nos. 5-165772 and 7-262033.
The conventional multi-array disk apparatus employs the plurality of array controllers 52 and 53 arranged for one logical drive 71 due to the double array controller arrangement, resulting in poor efficiency. Since the logical structure disks 57 and 58 have the same ID (IDentifier) in consideration of an artificial miss or maintenance, the two logical structure disks cannot be mounted on the same interface. Further, the control device IDs of the array controllers 52 and 53 for the logical drive 71 must be different from each other.
In the conventional multi-array disk apparatus, one of the array controllers 52 and 53 is normally unused, and no other logical drive is assigned under the array controller. For this reason, the multi-array disk apparatus has a normally unused array controller for one logical drive, resulting in poor efficiency.
Further, devices having the same ID cannot exist on a SCSI (Small Computer System Interface). When a fault is to be recovered by an array controller having another logical drive, the ID of the logical drive must be different from that of the array controller and that under the array controller, and must be changed by an artificial operation to complicate maintenance.